The assembly of a semiconductor package plays an important role in thermal management. A conventional semiconductor package includes a lid, one or more die, a die interconnect, a substrate, a substrate interconnect, and lid-attach thermal interface material (“TIM”).
The die is placed on the substrate through a die-attach process. Typically, the die-attach process involves attaching a flip-chip type die to the substrate by the die interconnect through a reflow process. The underfill is applied to the die interconnect, the die, and the substrate. The lid-attach TIM is applied to the bottom side of the die (the side opposite the die interconnect). The lid is placed on the substrate, typically making contact with the die by way of the lid-attach TIM. The semiconductor package is cured at a curing temperature. The bond line thickness (“BLT”) of the lid-attach TIM is determined by the co-planarity of the die, substrate, and lid, the application of the lid to the substrate, the characteristics of the lid-attach TIM, and the curing process of the assembled semiconductor package.
Conventional techniques for heat removal from a microprocessor, application specific integrated circuit (“ASIC”), integrated circuit (“IC”), or other printed circuit board (“PCB”) component rely upon the use of the heatsink-attach TIM placed between the heat generating device and a heat rejecting device. Typically, a single heat rejecting device, i.e., a heatsink, spans several components on the heat generating device, i.e., a semiconductor package. The BLT of the heatsink-attach TIM determines the thermal path performance and cooling efficiency of the heat rejecting device.